1. Field of the Invention
One embodiment of the present invention relates to a display device and a driving method of the display device.
In this specification, a semiconductor device means all types of devices which can function by utilizing semiconductor characteristics, and a semiconductor circuit, a memory device, an imaging device, a display device, an electro-optical device, an electronic device, and the like are all semiconductor devices.
2. Description of the Related Art
In recent years, display devices which can show pseudo stereoscopic images (three-dimensional images), such as a display device using a liquid crystal display device and a display device using an electroluminescent display device (also referred to as an EL display device), have been developed.
Examples of the display device which can show pseudo three-dimensional images include a display device making a viewer perceive two-dimensional images as three-dimensional images by utilizing parallax between the left eye and the right eye. In such a display device, for example, an image for the left eye (hereinafter referred to as a left-eye image) and an image for the right eye (hereinafter referred to as a right-eye image) are alternately displayed on a pixel portion, and a viewer sees the images with use of eyeglasses provided with shutters corresponding to both eyes. When a left-eye is displayed as a display image, the shutter for the right eye of the eyeglasses is closed, and light incident on the right eye of the viewer is blocked. When a right-eye image is displayed as a display image, the shutter for the left eye of the eyeglasses is closed, and light incident on the left eye of the viewer is blocked. As a result, two-dimensional images can be seen as pseudo three-dimensional images.
In addition, the following method (for example, Patent Document 1) is known. In each time of displaying a left-eye image and displaying a right-eye image, a unit frame period for displaying the image is divided into a plurality of subframe periods. A color of light emitted from a light unit (including a backlight) to a pixel circuit (also referred to as a display circuit) is changed every subframe period, whereby a full-color image is displayed every unit frame period (this method is called a field sequential method). When a field sequential method is employed, for example, a color filter is not needed in the liquid crystal display device, and thus, light transmittance can be increased.
In addition, a method in which the left-eye images and the right-eye images are each displayed continuously over a plurality of frame periods is known (for example, Patent Document 2). By the above method, an interval between operation of switching between a shutter for the left eye and a shutter for the right eye of the eyeglasses can be prolonged; thus, crosstalk can be suppressed even in the case of increasing the frame frequency.